Integration of SMP with PVDF Unimorph for Bending Enhancement

Heat generation in active/passive layer-based piezoelectric actuators is unavoidable due to the mechanical, dielectric, and resistive losses in the material. In this work, a polyvinylidene fluoride (PVDF)-based unimorph cantilever actuator is developed with simulation and experimental studies on the effect of DC high voltages on heat production in the PVDF layer. A layer of one-way shape memory polymers (1W-SMPs) is integrated in the actuator to exploit the heat produced to increase the bending angle. The length and mounting location of the SMP layer impacts the bending of the actuator; by using an SMP layer with a length equal to half of the PVDF layer at the center of the unimorph actuator, the absolute bending angle is increased to 40° compared to the base piezo bending angle of 4° at 20 V/µm.

Analysis of delamination of unimorph cantilever piezoelectric energy harvesters

Unimorph piezoelectric energy harvesters are typically a unimorph cantilever beam located on a vibrating host structure. Delamination is one of the major failure modes of such unimorph cantilevers and therefore is studied in this article. The delaminated cantilever unimorph is modeled with one through-width crack using four Euler beams connected at delamination edges. The governing equations, the corresponding boundary conditions, and the kinematic continuity conditions are derived based on the Hamiltonian principle. The solutions of the voltage and power output for the present model are derived. The influence of the position and the length of the delamination, frequency of input base excitation, and load resistance on the voltage and power output are discussed in detail. The results show that delamination in the unimorph of the energy harvester will impressively decrease the voltage and power outputs. Influences of the delamination located at the free end of the cantilever are more obvious. For a given active length of the delaminated cantilever energy harvester, it is useful to increase the overall length of the cantilever to obtain a higher voltage and power outputs.

Theoretical and Experimental Analysis of Dielectric Elastomer Unimorph Cantilever

Unimorph cantilever is widely used in many applications with its bending and tip-deflection. In this paper, a model of the cantilever with the applied voltage and tip-deflection is presented. With the use of this model, a prototype, fabricated by VHB and polycarbonate, is estimated for its bending tip-deflection under a high voltage. And the experiment system is established with a signal generator, high voltage amplifier and laser displacement meter. The experimental results and the theoretical ones are both the same. The conclusions in this paper can be used to make further research on the deformation control of structures.